Prep your onion Mise! Peel the outer layer and thinly slice onions.
In a large pot over medium low heat, add the butter and onions. Cover for 30 minutes stirring every 5 minutes. Remove lid and continue to cook until golden brown. This sould take a total of 45 minutes to 1 hour.
Meanwhile, mince garlic, pick and wash thyme and measure out wine and broth
Once the onions are golden, add garlic and salt and cook for 3-4 minutes.
Add the wine and cook for 5 minutes, until the wine has evaporated. Add the broth and thyme and simmer for 30 minutes.
Meanwhile, slice baguette inch thick and place on a baking sheet. Bake for 5 minutes at 350 ℉.
Grate the gruyere cheese.
Before pouring soup into bowls taste the seasoning, add salt if necessary. Place oven safe bowls on a baking sheet. Pour soup 2 inches from the lip of the bowl. Top with bread and cheese (see pro tip above).
Turn oven to broil and place the baking sheet with the soup bowls in the oven. Broil for 5 minutes or until the top is golden and crispy.
Serve piping hot! However, make sure to warn your guests that the bowls are friggen hot!